Smart power saving mode – intelligent use of power saving which automatically reduces the measurement time for high flow velocities and high signal qualities and increases the measurement time for low velocities and low signal qualities

Sophisticated ultrasound processing ignores spurious signals

Ultrasound signal quality monitor confirms measurement integrity

Specified (constant) silt level taken into account in area calculation

Velocity correction factor calibration

Automatic recording of velocity signals and histograms for use in performance monitoring or reports

Distances up to 500 m from system unit to velocity and level sensor. 300 m for ATEX velocity and level sensor

Opto-isolated switch outputs for alarms and controls

Mainstream uses the area-velocity method to give a continuous or time sample measurement of fluid flow. Mainstream uses a streamlined probe that operates immersed in the flowing liquid. The velocity probe transmits utrasound into the liquid to create a zone of inspection. Bubbles and solid particles carried through this zone by the flow, even when present in only minute quantities, reflect ultrasound back to the probe. Only high quality signals containing verified velocity information is used, thereby ensuring measurement integrity.

This measured frequency shift in the ultrasound signals gives flow velocity. The verified velocity signals produce a histogram of the flow velocities. Analysing this histogram gives the mean flow velocity.

Liquid level is measured by a submerged pressure transmitter or ultrasonic sensor. The flow cross-sectional area is deduced from the liquid level measurement and the stored description of the channel or pipe cross section. The flow rate is the flow velocity multiplied by the flow cross-sectional area.

VELOCITY MEASUREMENT

Phase Coherence time delay measurement determines the time for tracers carried by the flow to travel a fixed distance (~ 0.75 mm)

Velocity Range :

-5 m/s to -10 mm/s and 10 mm/s to 5 m/s

Resolution :

Better than 1 mm/s

Measurement Integrity :

Ultrasound signal quality monitor gives the percentage of the measurement time that the received ultrasound signal contains useful velocity information

Smart Power Saving :

Each velocity measurement is based on the same quantity of information. Automatically reduces the measurement time for high flow velocities and high signal qualities and increases the measurement time for low velocities and low signal qualities

DERIVED MEASUREMENTS

Area :

Flow cross-sectional area calculated from the level measurement and the dimensions of the pipe or channel. Calculation can take into account a specified (constant) silt level. Flow cross-section specification tools included in UI software

USER INTERFACES

Reset Switch :

Push to Reset LCD display

LCD :

Two line x 16 character LCD. Automatic activation when integral light sensor detects enclosure is open. Configurable display sequence includes date, time, and any combination of measurement data. Country specific caption text and date/time format

Independently configurable display format for each measurement. Options are integer, fixed point with 1 to 6 decimal places, and scientific (E-format). Display defaults to scientific format if data cannot be correctly represented in selected format

SWITCH OUTPUTS

Hardware :

Two opto-isolated switches rated at 60V ac/dc and 200 mA maximum current. Each switch independently configurable for state output or pulse output operation

State Output :

Switch configurable to respond to any item of measured data with separate switch open and switch close settings to provide hysterisis. Applications include power supply monitoring and control, low ultrasound signal quality indication and level, velocity and flow alarms

Pulse Output :

Switch configurable to generate a 2.5 second duration switch closure to indicate a defined flow quantity. Flow totaliser can be forward only, reverse only, or forward- reverse. Applications include sampler control and remote flow totaliser operation

4:20mA Outputs :

One 4:20 mA output. Configurable to selected measurands

PTX LEVEL SENSOR

Materials :

Titanium, acetal and polyurethane

Dimensions :

185 mm long x 17.5 mm diameter

Cable :

8 mm diameter vented polyurethane cable with Kevlar strain cord

Weight :

1 kg including standard 10 m cable length

Level Range :

0 to 2 m working. Maximum 8m overrange

Resolution :

Better than 1mm

Combined Accuracy :

Combined effects of non-linearity, hysterisis and repeatability better than 0.25% best straight line. Non-linearity and offsets removed by transducer calibration